The need to support and provide different services has led the development of telecommunication networks in the direction of what is known as an Intelligent Network IN. An intelligent network can be defined as architecture that is applicable to most telecommunication networks, irrespective of network technology. The aim is to create, control and manage teleservices giving added value. One characteristic of the intelligent network is to provide modular functions that are independent of a service used and can be connected to one another as components when new services are provided, which makes it easier to define and design new services. Another characteristic is that the supply of services is independent of the telecommunication network. The services are separate from the lowest physical network structure, whereby they may be distributed.
In recommendation CS-1 (Capability Set 1), CCITT defines an Intelligent Network Conceptual Model INCM. The model consists of four levels, each of which represents an abstract view of the possibilities offered by the intelligent network. The second highest level in the model is a Global Functional Plane, and it includes the view of the intelligent network as Service Independent Building Blocks SIB, from which desired features of a service and desired services are assembled by the use of service logic. This level also comprises a Basic Call Process BCP, which covers the whole network, and a Point of Initiation POI and a Point of Return POR between BCP and SIB.
A Service Switching Point SSP gives the user access to the network and makes all the necessary selections. It is able to detect the service requests of the intelligent network. Operationally, SSP contains call management and service selection functions. A Service Control Point SCP comprises the programs of the service logic that are used for producing intelligent network services. A Service Data Point SDP contains the data that the programs of the SCP service logic use to produce individualized services. SCP and/or SMP can use the services of SDP either directly or via a signalling network that uses an INAP protocol. Supplementary services offered by an Intelligent Peripheral IP include e.g. voice messages, synthetic voice and speech detection means, and voice generation. A Service Switching and Control Point SSCP consists of SCP and SSP in one node. A Service Management Point controls the service management, supply and performance, and can be connected to all other physical entities. Examples for the operation include database management, network control and testing, network traffic management, and network data collection. A Service Creation Environment Point SCEP is used for defining, developing and testing intelligent network services, and for supplying the service to SMP. An Adjunct AD corresponds operationally to the service control point SCP but is connected directly to SSP. A Service Node SN can control the intelligent network services, and it communicates with the users. It communicates directly with one or more SSPs. A Service Management Access Point SMAP is a physical entity that provides certain users with a connection to SMP.
A Basic Call State Model BCSM defined in connection with the intelligent network is a description of the facilities of the call management function needed for setting up and maintaining a connection between users. It detects the points (detection point) in the call and connection process in which the IN service logic entities can interact with the basic call and connection management functions. It provides a basis for describing the basic call and connection actions that may lead to activation of an IN service logic entity and description of the points where the transfer of the control may be performed.
FIG. 2 illustrates one known basic service in an intelligent network, i.e. number conversion service. Only essential physical entities are shown in the figure. The subscriber inputs e.g. the number 800+ABCD (ABCD is a number sequence). Upon detecting the prefix 800, the call control function of the exchange identifies the call as an intelligent network call, whereby it requests for an intelligent network service via the intelligent network Service Switching Point SSP. Using common channel signalling, it sends the control point SCP an inquiry containing the number 800+ABCD. The service program of the SCP checks the SDP file to see what number of a conventional telephone network corresponds to the number 800+ABCD. In this example, the number is 291 7041. SCP sends this number to SSP, which forwards it to the call control of the exchange, which then routes the call to the number concerned. In sending the number to SSP, SCP also sends charging information on the call. The exchange generates pulses during the call, and the call is later charged for on the basis of these pulses and the charging information provided by SCP.
Another example for an intelligent network service is Automatic Alternative Billing AAB. It makes it possible for the user to make a call from any phone whatsoever, the call being later debited against the user's account, which is maintained by the operator, and the charging being implemented as aftercharging. The provider of the service allocates an Account Code to the user of the service, and a Personal Identification Number PIN. The service will be activated as the user inputs the access code, followed by the number that the user wants to call. SSP identifies the access code and transfers the control to SCP. SCP asks the user to input the account code and PIN. The code and PIN inputted by the user are checked by a database inquiry, after which the call is connected. The bill for the call is formed afterwards on the basis of the charging information provided by SCP and the pulses generated by the exchange.
Irrespective of the fact whether the subscriber uses the intelligent network service or not, and whether he is a mobile subscriber or a fixed network subscriber, it is typical of the present telephone systems that different subscriber databases are used and that call- and subscriber-specific charging is implemented as aftercharging. A fixed network typically uses the subscriber database of an exchange; and a mobile phone network, such as a GSM network, uses a Home Location Register HLR, in which permanent subscriber data are stored. The abovementioned AAB service uses a database of an intelligent network, the database containing the account number and PIN.
The feature common to all these subscriber databases is that they are created and updated by the operator of the network concerned. As known, different subscriber-specific parameters can be set in the database. For example, the network operator can set in the subscriber record a parameter that prevents the subscriber from making e.g. international calls or denies access to certain services implemented by means of an intelligent network, e.g. entertainment services. Entertainment services implemented by an intelligent network have proved particularly problematic, and so it has been possible to set a certain time limit at which the call will be terminated.
In view of the above, subscriber administration of the present networks seems to involve some problems. It is not possible to include a parameter that would prohibit over-expensive calls in the subscriber databases, since the subscriber is never charged until afterwards, after the call. The only possibility is to deny access altogether to numbers that begin with certain prefixes. Since it is not possible to receive real time information about an on-going call made by a subscriber, e.g. charging information and statistical data, the calls of a so-called problem subscriber cannot be controlled during the call. In mobile phone networks, it is at present not possible to separately control visitor subscriber traffic, but a visitor subscriber coming from another network can make phone calls and leave them unpaid, thereby making the operator suffer losses. A time limit for entertainment services, implemented in intelligent networks, is specific for the call and thereby applies to all calls to an entertainment number, so it does not prevent the subscriber from dialling service a plural number of times, since subscriber-specific or subscriber-connection-specific control has so far not been possible.